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Bieniek H, Bąbel P. Placebo hypoalgesia induced by operant conditioning: a comparative study on the effects of verbal, token-based, and social rewards and punishers. Sci Rep 2023; 13:20346. [PMID: 37989856 PMCID: PMC10663593 DOI: 10.1038/s41598-023-47482-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 11/14/2023] [Indexed: 11/23/2023] Open
Abstract
Operant conditioning was shown to be a mechanism of placebo hypoalgesia; however, only verbal rewards and punishers were applied in the previous study. We aimed to induce placebo hypoalgesia using more clinically relevant consequences: token-based and social. Participants were divided into three experimental groups (with verbal, social, and token-based rewards and punishers); and two control groups (with and without placebo application). During operant conditioning, participants in the experimental groups received thermal stimuli of equal intensity and were rewarded for reporting lower pain and punished for reporting higher pain compared to their pretest pain levels. The control groups did not receive any consequences. Our results revealed placebo hypoalgesia was induced by operant conditioning only in the experimental groups with social and token-based reinforcement, compared to the control groups. The hypoalgesic effect found in the group that received verbal reinforcement did not differ significantly from the control group with the placebo application. Moreover, expectations about upcoming pain intensity were found to be a mediator, and the number of reinforcers received during conditioning was a predictor of placebo hypoalgesia. These findings highlight the potential benefits of incorporating token-based and social consequences for optimizing treatment outcomes in pain management.
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Affiliation(s)
- Helena Bieniek
- Institute of Psychology, Pain Research Group, Jagiellonian University, ul. Ingardena 6, 30-060, Kraków, Poland.
- Doctoral School in the Social Sciences, Jagiellonian University, Kraków, Poland.
| | - Przemysław Bąbel
- Institute of Psychology, Pain Research Group, Jagiellonian University, ul. Ingardena 6, 30-060, Kraków, Poland
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Luebke L, Gouverneur P, Szikszay TM, Adamczyk WM, Luedtke K, Grzegorzek M. Objective Measurement of Subjective Pain Perception with Autonomic Body Reactions in Healthy Subjects and Chronic Back Pain Patients: An Experimental Heat Pain Study. SENSORS (BASEL, SWITZERLAND) 2023; 23:8231. [PMID: 37837061 PMCID: PMC10575054 DOI: 10.3390/s23198231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/15/2023]
Abstract
Multiple attempts to quantify pain objectively using single measures of physiological body responses have been performed in the past, but the variability across participants reduces the usefulness of such methods. Therefore, this study aims to evaluate whether combining multiple autonomic parameters is more appropriate to quantify the perceived pain intensity of healthy subjects (HSs) and chronic back pain patients (CBPPs) during experimental heat pain stimulation. HS and CBPP received different heat pain stimuli adjusted for individual pain tolerance via a CE-certified thermode. Different sensors measured physiological responses. Machine learning models were trained to evaluate performance in distinguishing pain levels and identify key sensors and features for the classification task. The results show that distinguishing between no and severe pain is significantly easier than discriminating lower pain levels. Electrodermal activity is the best marker for distinguishing between low and high pain levels. However, recursive feature elimination showed that an optimal subset of features for all modalities includes characteristics retrieved from several modalities. Moreover, the study's findings indicate that differences in physiological responses to pain in HS and CBPP remain small.
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Affiliation(s)
- Luisa Luebke
- Institute of Health Sciences, Department of Physiotherapy, Pain and Exercise Research Luebeck (P.E.R.L.), Universität zu Lübeck, 23562 Lübeck, Germany; (L.L.); (T.M.S.); (K.L.)
- Center of Brain, Behavior and Metabolism (CBBM), University of Luebeck, 23562 Lübeck, Germany
| | - Philip Gouverneur
- Institute of Medical Informatics, University of Lübeck, 23562 Lübeck, Germany;
| | - Tibor M. Szikszay
- Institute of Health Sciences, Department of Physiotherapy, Pain and Exercise Research Luebeck (P.E.R.L.), Universität zu Lübeck, 23562 Lübeck, Germany; (L.L.); (T.M.S.); (K.L.)
- Center of Brain, Behavior and Metabolism (CBBM), University of Luebeck, 23562 Lübeck, Germany
| | - Wacław M. Adamczyk
- Laboratory of Pain Research, Institute of Physiotherapy and Health Sciences, The Jerzy Kukuczka Academy of Physical Education, 40-065 Katowice, Poland;
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229-3026, USA
| | - Kerstin Luedtke
- Institute of Health Sciences, Department of Physiotherapy, Pain and Exercise Research Luebeck (P.E.R.L.), Universität zu Lübeck, 23562 Lübeck, Germany; (L.L.); (T.M.S.); (K.L.)
- Center of Brain, Behavior and Metabolism (CBBM), University of Luebeck, 23562 Lübeck, Germany
| | - Marcin Grzegorzek
- Institute of Medical Informatics, University of Lübeck, 23562 Lübeck, Germany;
- Department of Knowledge Engineering, University of Economics in Katowice, 40-287 Katowice, Poland
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Thomaidou MA, Blythe JS, Peerdeman KJ, van Laarhoven AIM, Van Schothorst MME, Veldhuijzen DS, Evers AWM. Learned Nocebo Effects on Cutaneous Sensations of Pain and Itch: A Systematic Review and Meta-analysis of Experimental Behavioral Studies on Healthy Humans. Psychosom Med 2023; 85:308-321. [PMID: 36961347 PMCID: PMC10171297 DOI: 10.1097/psy.0000000000001194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 01/24/2023] [Indexed: 03/25/2023]
Abstract
OBJECTIVE In past decades, the field of nocebo research has focused on studying how sensory perception can be shaped by learning. Nocebo effects refer to aggravated sensory experiences or increased sensitivity to sensations such as pain and itch resulting from treatment-related negative experiences. Behavioral conditioning and verbal suggestions of a negative treatment outcome may aggravate pain and itch perception. Gaining a comprehensive view of the magnitude of nocebo effects and contributing factors will help steer nocebo research toward fruitful directions for understanding complex sensory phenomena. METHODS We conducted a systematic review and meta-analysis of a total of 37 distinct experimental nocebo studies on healthy participants (all published in English between 2008 and 2021), with four separate meta-analyses for nocebo effects on pain or itch. We conducted subgroup analyses and meta-regression on factors such as type and intensity of sensory stimuli, and length of conditioning paradigms. RESULTS This meta-analysis showed that, on average, effect sizes of nocebo effects were moderate to large (Hedges g between 0.26 and 0.71 for the four primary outcomes). The combination of conditioning and verbal suggestions yielded stronger nocebo responses on pain in particular. Subgroup analyses, including factors such as the type of sensory stimulation, did not explain the moderate heterogeneity in nocebo magnitudes between different studies. Risk of bias was generally low and was not related to nocebo magnitudes either. CONCLUSIONS We discuss these results in relation to the role of conditioning and aversive learning, and we recommend more consistency in designing and reporting nocebo experiments.
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Is Pain Contagious? Innocuous Stimulation Can be Transformed Into the Pain Experience by Observational Learning. THE JOURNAL OF PAIN 2022; 23:2135-2143. [PMID: 35970444 DOI: 10.1016/j.jpain.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 07/13/2022] [Accepted: 07/31/2022] [Indexed: 01/04/2023]
Abstract
Studies indicate that classical and operant conditioning have potential to play a role in the formation of the allodynic effect. Only a few studies have examined the role of observational learning in pain induction. Due to some methodological challenges, evidence that the allodynic effect can be learned through observation is limited. In the present study, healthy participants (n = 88) received 2 series of innocuous electrocutaneous stimuli: at the beginning of the study and after observation of a model who rated all the stimuli as painful. Participants and the model rated all the stimuli alternately (real-time group), or the participant first observed the model and then rated the stimuli, while the model stayed in (post-hoc+ group) or left (post-hoc- group) the laboratory. There was no model in the control group. The study demonstrated that allodynia can be induced by observational learning. Furthermore, this effect was shown to be similar, regardless of whether stimuli were received during the observation of the model and rated immediately afterwards, or when the observation and stimuli reception were time-separated. The mere presence of the model during the stimuli reception also did not affect the magnitude of this effect. This research may contribute to our understanding of the mechanisms of chronic pain development and assist in the development of suitable treatment for it. PERSPECTIVE: This article presents study results on the role of observational learning in allodynia induction without tissue injury. The results may contribute to our understanding of the mechanisms of chronic pain development and assist in the development of suitable treatment for it.
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Brazenor GA, Malham GM, Teddy PJ. Can Central Sensitization after injury persist as an autonomous pain generator? - A comprehensive search for evidence. PAIN MEDICINE 2021; 23:1283-1298. [PMID: 34718773 DOI: 10.1093/pm/pnab319] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 10/11/2021] [Accepted: 10/21/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To conduct a comprehensive search for evidence whether Central Sensitization following an injury can act as a persistent autonomous pain generator after the inducing injury has healed. METHODS We searched Medline on PubMed and the Cochrane Library, screening 3,572 abstracts, from which 937 full text articles were obtained, with 186 of these discarded as irrelevant to the question being posed. The remaining 751 articles were studied for evidence. RESULTS Fourteen publications were judged to provide weak evidence for the hypothesis of central sensitization as a persisting autonomous pain generator, but none addressed the question directly. No strong evidence for the affirmative answer was found.Sixty-two publications were judged to provide weak evidence for a negative answer, and nine judged to provide strong evidence.Unexpectedly, serious weaknesses were discovered in the literature underpinning the validity of the clinical diagnosis of Central Sensitization in man:(i) Inappropriate extrapolation, in many publications, of laboratory animal data to humans.(ii) Failure to demonstrate the absence of peripheral pain generators which might be perpetuating Central Sensitization.(iii) Many factors now shown to confound what is being measured by quantitative sensory testing, conditioned pain modulation, and Central Sensitization Inventory. CONCLUSIONS We found no evidence proving that central sensitization can persist as an autonomous pain generator after the initiating injury has healed.Our review has also shown that the evidential basis for the diagnosis of CS in individual patients is seriously in question.
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Affiliation(s)
| | | | - Peter J Teddy
- Royal Melbourne Hospital, Parkville, Victoria, Australia
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Ma M, Wang Z, Wang J, Wei S, Cui J, Wang Y, Luo K, Zhao L, Liu X, Wang R. Endomorphin analog exhibited superiority in alleviating neuropathic hyperalgesia via weak activation of NMDA receptors. J Neurochem 2020; 155:662-678. [DOI: 10.1111/jnc.15127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 06/10/2020] [Accepted: 07/11/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Mengtao Ma
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Zhaojuan Wang
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Jing Wang
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Shuang Wei
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Jiaming Cui
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Yuan Wang
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Keyao Luo
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Long Zhao
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Xin Liu
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
| | - Rui Wang
- Department of Pharmacology Key Laboratory of Preclinical Study for New Drugs of Gansu Province Institute of Biochemistry and Molecular BiologySchool of Basic Medical SciencesLanzhou University Lanzhou China
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D’Amico R, Impellizzeri D, Cuzzocrea S, Di Paola R. ALIAmides Update: Palmitoylethanolamide and Its Formulations on Management of Peripheral Neuropathic Pain. Int J Mol Sci 2020; 21:ijms21155330. [PMID: 32727084 PMCID: PMC7432736 DOI: 10.3390/ijms21155330] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 02/06/2023] Open
Abstract
Neuropathic pain results from lesions or diseases of the somatosensory nervous system and it remains largely difficult to treat. Peripheral neuropathic pain originates from injury to the peripheral nervous system (PNS) and manifests as a series of symptoms and complications, including allodynia and hyperalgesia. The aim of this review is to discuss a novel approach on neuropathic pain management, which is based on the knowledge of processes that underlie the development of peripheral neuropathic pain; in particular highlights the role of glia and mast cells in pain and neuroinflammation. ALIAmides (autacoid local injury antagonist amides) represent a group of endogenous bioactive lipids, including palmitoylethanolamide (PEA), which play a central role in numerous biological processes, including pain, inflammation, and lipid metabolism. These compounds are emerging thanks to their anti-inflammatory and anti-hyperalgesic effects, due to the down-regulation of activation of mast cells. Collectively, preclinical and clinical studies support the idea that ALIAmides merit further consideration as therapeutic approach for controlling inflammatory responses, pain, and related peripheral neuropathic pain.
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Affiliation(s)
- Ramona D’Amico
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D’Alcontres 31, 98166 Messina, Italy; (R.D.); (D.I.); (R.D.P.)
| | - Daniela Impellizzeri
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D’Alcontres 31, 98166 Messina, Italy; (R.D.); (D.I.); (R.D.P.)
| | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D’Alcontres 31, 98166 Messina, Italy; (R.D.); (D.I.); (R.D.P.)
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, 1402 South Grand Blvd, St Louis, MO 63104, USA
- Correspondence: ; Tel.: +39-90-6765208
| | - Rosanna Di Paola
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D’Alcontres 31, 98166 Messina, Italy; (R.D.); (D.I.); (R.D.P.)
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Abstract
Pain is considered a hardwired signal of bodily disturbance belonging to a basic motivational system that urges the individual to act and to restore the body's integrity, rather than just a sensory and emotional experience. Given its eminent survival value, pain is a strong motivator for learning. Response to repeated pain increases when harm risks are high (sensitization) and decreases in the absence of such risks (habituation). Discovering relations between pain and other events provides the possibility to predict (Pavlovian conditioning) and control (operant conditioning) harmful events. Avoidance is adaptive in the short term but paradoxically may have detrimental long-term effects. Pain and pain-related responses compete with other demands in the environment. Exposure-based treatments share the aim of facilitating or restoring the pursuit of individual valued life goals in the face of persistent pain, and further improvements in pain treatment may require a paradigm shift toward more personalized approaches.
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Affiliation(s)
- Johan W S Vlaeyen
- Research Group on Health Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium; .,Experimental Health Psychology, Maastricht University, 6211 LK Maastricht, The Netherlands
| | - Geert Crombez
- Department of Experimental-Clinical and Health Psychology, Faculty of Psychology and Educational Sciences, Ghent University, 9000 Ghent, Belgium.,Centre for Pain Research, University of Bath, Bath BA2 7AY, United Kingdom
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Bąbel P. Operant conditioning as a new mechanism of placebo effects. Eur J Pain 2020; 24:902-908. [PMID: 32060991 DOI: 10.1002/ejp.1544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 12/23/2019] [Accepted: 02/12/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND OBJECTIVE Placebo effects are considered to be learning phenomena. There is a growing body of evidence supporting the role of both classical conditioning and observational learning in the induction of placebo effects. However, the third basic learning process, operant conditioning, was not considered as a mechanism of placebo effects until very recently. Unlike classically conditioned responses, which are induced by stimuli that precede the behaviour, operant behaviours are shaped and maintained by their consequences. Thus, placebo effects may not only result from pairing an active intervention with the stimuli that accompany its administration (placebo) but also positive (e.g. the ability to perform a desired activity) or negative reinforcement (e.g. pain relief) of placebo administration may increase the frequency of taking placebos in the future. The paper reviews the evidence supporting the idea of operant conditioning as a mechanism of placebo effects and discusses it in the context of the general principles of operant conditioning, the operant conditioning account of pain modulation and research findings on the role of operant conditioning in pain modulation. DATABASES AND DATA TREATMENT This is a narrative review. RESULTS Seven lines of research are proposed to study the role of operant conditioning in producing placebo effects. CONCLUSIONS Operant conditioning account of placebo effects has practical implications both for routine clinical practice and the placebo arms of randomized controlled trials. SIGNIFICANCE The operant conditioning account of placebo effects is discussed from the theoretical perspective of the general principles of operant conditioning and the operant conditioning account of pain modulation. The paper identifies seven lines of research on the role of operant conditioning in producing placebo effects, and highlights the practical implications of the operant conditioning account of placebo effects both for routine clinical practice and the placebo arms of randomized controlled trials.
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Affiliation(s)
- Przemysław Bąbel
- Pain Research Group, Institute of Psychology, Jagiellonian University, Kraków, Poland
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